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|
use crossterm::event::{self, Event, KeyCode, KeyEvent, KeyEventKind};
use miette::{Diagnostic, IntoDiagnostic, Result};
use ratatui::{
DefaultTerminal, Frame,
buffer::Buffer,
layout::Rect,
style::Stylize,
symbols::border,
text::{Line, Text},
widgets::{Block, Paragraph, Widget},
};
use thiserror::Error;
#[derive(Debug, Default)]
pub struct App {
counter: u8,
exit: bool,
}
#[derive(Diagnostic, Debug, Error, PartialEq)]
#[error("An overflow error occurred")]
#[diagnostic()]
pub struct OverflowError {
#[help]
_msg: String,
}
fn main() -> Result<()> {
ratatui::run(|term| App::default().run(term))
}
impl App {
/// runs the application's main loop until the user quits
pub fn run(&mut self, terminal: &mut DefaultTerminal) -> Result<()> {
while !self.exit {
terminal.draw(|frame| self.draw(frame)).into_diagnostic()?;
self.handle_events()?;
}
Ok(())
}
fn draw(&self, frame: &mut Frame) {
frame.render_widget(self, frame.area());
}
fn handle_events(&mut self) -> Result<()> {
match event::read().into_diagnostic()? {
// it's important to check that the event is a key press event as
// crossterm also emits key release and repeat events on Windows.
Event::Key(key_event) if key_event.kind == KeyEventKind::Press => {
self.handle_key_event(key_event)
}
_ => Ok(()),
}
}
fn handle_key_event(&mut self, key_event: KeyEvent) -> Result<()> {
match key_event.code {
KeyCode::Char('q') => self.exit()?,
KeyCode::Left => self.decrement_counter()?,
KeyCode::Right => self.increment_counter()?,
_ => {}
};
Ok(())
}
fn exit(&mut self) -> Result<()> {
self.exit = true;
Ok(())
}
fn decrement_counter(&mut self) -> Result<(), OverflowError> {
if self.counter == 0 {
Err(OverflowError {
_msg: "Cannot count below 0".into(),
})
} else {
self.counter -= 1;
Ok(())
}
}
fn increment_counter(&mut self) -> Result<(), OverflowError> {
if self.counter == u8::MAX {
Err(OverflowError {
_msg: "Cannot count above u8::MAX".into(),
})
} else {
self.counter += 1;
Ok(())
}
}
}
impl Widget for &App {
fn render(self, area: Rect, buf: &mut Buffer) {
let title = Line::from(" Counter App Tutorial ".bold());
let instructions = Line::from(vec![
" Decrement ".into(),
"<Left>".blue().bold(),
" Increment ".into(),
"<Right>".blue().bold(),
" Quit ".into(),
"<Q> ".blue().bold(),
]);
let block = Block::bordered()
.title(title.centered())
.title_bottom(instructions.centered())
.border_set(border::THICK);
let counter_text = Text::from(vec![Line::from(vec![
"Value: ".into(),
self.counter.to_string().yellow(),
])]);
Paragraph::new(counter_text)
.centered()
.block(block)
.render(area, buf);
}
}
#[cfg(test)]
mod tests {
use super::*;
use ratatui::style::Style;
#[test]
fn render() {
let app = App::default();
let mut buf = Buffer::empty(Rect::new(0, 0, 50, 4));
app.render(buf.area, &mut buf);
let mut expected = Buffer::with_lines(vec![
"┏━━━━━━━━━━━━━ Counter App Tutorial ━━━━━━━━━━━━━┓",
"┃ Value: 0 ┃",
"┃ ┃",
"┗━ Decrement <Left> Increment <Right> Quit <Q> ━━┛",
]);
let title_style = Style::new().bold();
let counter_style = Style::new().yellow();
let key_style = Style::new().blue().bold();
expected.set_style(Rect::new(14, 0, 22, 1), title_style);
expected.set_style(Rect::new(28, 1, 1, 1), counter_style);
expected.set_style(Rect::new(13, 3, 6, 1), key_style);
expected.set_style(Rect::new(30, 3, 7, 1), key_style);
expected.set_style(Rect::new(43, 3, 4, 1), key_style);
assert_eq!(buf, expected);
}
#[test]
fn handle_key_event_inc_dec() {
let mut app = App::default();
let res = app.handle_key_event(KeyCode::Right.into());
assert!(res.is_ok());
assert_eq!(app.counter, 1);
let res = app.handle_key_event(KeyCode::Left.into());
assert!(res.is_ok());
assert_eq!(app.counter, 0);
}
#[test]
fn handle_key_event_exit() {
let mut app = App::default();
let res = app.handle_key_event(KeyCode::Char('q').into());
assert!(res.is_ok());
assert!(app.exit);
}
#[test]
fn handle_key_event_dec_error() {
let mut app = App::default();
let res = app.handle_key_event(KeyCode::Left.into());
assert!(res.is_err());
let res_err = res.unwrap_err();
let casted_val = res_err
.downcast_ref::<OverflowError>()
.expect("something bad occurred");
let expected_err_msg: String = "Cannot count below 0".into();
assert_eq!(casted_val._msg, expected_err_msg);
assert_eq!(
*casted_val,
OverflowError {
_msg: expected_err_msg,
},
);
}
#[test]
fn handle_key_event_inc_error() {
let mut app = App::default();
app.counter = u8::MAX;
let res = app.handle_key_event(KeyCode::Right.into());
assert!(res.is_err());
let res_err = res.unwrap_err();
let casted_val = res_err
.downcast_ref::<OverflowError>()
.expect("something bad occurred");
let expected_err_msg: String = "Cannot count above u8::MAX".into();
assert_eq!(casted_val._msg, expected_err_msg);
assert_eq!(
*casted_val,
OverflowError {
_msg: expected_err_msg,
},
);
}
}
|
